The invention generally relates to methods for preparing compounds useful as kinase inhibitors or alternatively, as components or precursors in the synthesis of kinase inhibitors.
Pyrrolotriazine compounds useful as kinase inhibitors are disclosed in co-pending U.S. patent application Ser. No. 09/573,829, filed May 18, 2000, which is commonly assigned with this application. Pyrrolotriazine compounds useful as kinase inhibitors are also disclosed in U.S. Pat. No. 6,670,357, assigned to the present assignee, and the following co-pending patent applications, each of which also is commonly assigned with this application: U.S. patent application Ser. Nos. 10/289,010, filed Nov. 6, 2002 (U.S. Pub. No. 20030186982A1), 10/420,399, filed Mar. 22, 2003 (WO 03/090912), 10/420,445, filed Apr. 22, 2003 (U.S. Pub. No. 20030232831A1), 10/633,997, filed Aug. 4, 2003, 10/623,171, filed Jul. 18, 2003, and 10/678,388, filed Oct. 3, 2003.
Pyrrolotriazine compounds substituted with an acidic group reportedly having sPLA2-inhibitory activity are disclosed in WO 01/14378 A1 to Shionogi & Co., Ltd, published Mar. 1, 2001 in Japanese. The entire disclosure of each of the patent applications, patents, and publications referred to herein is incorporated herein by reference.
Desirably, useful processes for producing such compounds would utilize commercially available starting materials to minimize costs, and would also reduce the reliance on more toxic reactants, while maintaining acceptable product yields. Such processes are described and claimed herein.

and pharmaceutically-acceptable salts, solvates, and/or prodrugs thereof, wherein
R1 and R2 are independently selected from hydrogen and alkyl;
R3 is attached to any available carbon atom of the phenyl ring and at each occurrence is independently selected from hydrogen, alkyl, substituted alkyl, halogen, cyano, nitro, amino, hydroxy, alkoxy, and substituted alkoxy;
R4 is hydrogen, alkyl, aryl, or heteroaryl;
R5 is hydrogen, alkyl, aryl, or heteroaryl;
R6 is hydrogen, alkyl, aryl, or heteroaryl;
R7 and R8 are
(i) independently selected from hydrogen, alkyl or substituted alkyl, alkenyl or substituted alkenyl, cycloalkyl or substituted cycloalkyl, aryl or substituted aryl, heteroaryl or substituted heteroaryl, and heterocyclic or substituted heterocyclic; or
(ii) R7 and R8 can be taken together with the nitrogen atom to which they are attached to form a heterocyclic or substituted heterocyclic group or a heteroaryl or substituted heteroaryl group; said group formed optionally containing an additional 1 or 2 heteroatoms; and
n is 0, 1 or 2,
are effective kinase inhibitors. They exhibit utility in treating inflammatory conditions by inhibiting p38 α and/or β enzymes, and inhibiting TNF-α.
WO 00/71129 describes the preparation of 1,4-dihydro-5-alkyl-4-oxo-pyrrolo[2,1-f][1,2,4]triazine-6-carboxylates, key intermediates in the synthesis of pyrrolotriazine carboxamide and benzamide compounds of formula I, by reacting a Michael acceptor such as methyl crotonate with an anion of tosylmethyl isocyanide (TosMIC) to give 4-methylpyrrole-3-carboxylic acid methyl ester. The resulting 4-methylpyrrole-3-carboxylic acid methyl ester is acylated with trichloroacetyl chloride in the presence of aluminum chloride to afford 2-trichloroacetyl-3-methylpyrrole-4-carboxylic acid methyl ester. Treatment of 2-trichloroacetyl-3-methylpyrrole-4-carboxylic acid methyl ester with sodium methoxide produces 3-methylpyrrole-2,4-dicarboxylic acid methyl ester. N-amination of 3-methylpyrrole-2,4-dicarboxylic acid methyl ester using an aminating reagent such as diphenyl phosphoryl hydroxylamine affords 1-amino-3-methylpyrrole-2,4-dicarboxylic acid methyl ester. Finally, reaction of 1-amino-3-methylpyrrole-2,4-dicarboxylic acid methyl ester with formamide at elevated temperature gives 1,4-dihydro-5-methyl-4-oxo-pyrrolo[2,1-f][1,2,4]triazine-6-carboxylic acid methyl ester (Hunt, J. T.; Bhide, R. S.; Borzilleri, R. M.; Qian, L. WO 00/71129, Nov. 30, 2000). Although a number of 1,4-dihydro-5-substitued-4-oxo-pyrrolo[2,1-f][1,2,4]triazine-6-carboxylates can be prepared by this method, this process is limited due to its lengthy chemical transformations, the use of hazardous aminating reagents and expensive chromatographic separation of products. WO 02/40486 describes an improved synthesis of 3-methylpyrrole-2,4-dicarboxylates by condensing ethaldehyde and isocyanoacetates in the presence of DBU. The synthesis is shorter, however, generation of the side-product, cyanide, is a safety concern. Preparation of 6-ethyl-1,2,4-triazin-5-one by Raney nickel mediated desulfurization of 6-ethyl-1,2,4-triazin-5-one-3-thione has been reported (Taft, W. E.; Shepherd, R. G. J. Med. Chem. (1967), 10, at 883).